Automatic air-brake.



No. 635,995. Patented Oct. 3|, I899. W. H. CLARKE.

AUTOMATIC AIR BRAKE.

(Application filed May 9, 1898.)

(No Model.)

WITNESSES: INVENTOB mi NQRRIS PEIERS ca. vnoroumo summon, an

UNITED STATES WILLIAM H. CLARKE,

OF NEW YORK, N. Y.

AUTOMATIC AIR-BRAKE.

SPECIFICATION forming part of Letters Patent No. 635,995, dated October31, 1899.

Application filed May 9, I898, Serial No. 680,085. (No model.)

T0 to whom it may concern:

Be it known that 1, WILLIAM CLARKE, a citizen of the United States,residing at the city of New York, in the borough of Brooklyn and Stateof New York, have invented certain new and useful Improvements inAutomatic Air-Brakes, of which the following is a full, clear, and exactdescription. 1

This invention relates to automatic fluidpressure train-brakes. Itsobject is to furnish means by which a high braking force may be utilizedwhen desired without injuri= ous effects-such, forinstance, as thelocking or sliding of wheels, which frequently takes place at moderatespeeds when excessive pressure is applied to the brake-shoes.

Experiment in the art has demonstrated that when a train is at fullspeed a higher pressure may be safely applied to the brakeshoes withoutlocking and sliding the wheels than when the momentum of the train hasbeen nearly checked. It is therefore evident that the maximum efficiencyof the brakes will be obtained if an excessive pressure is used at highspeed and gradually reduced as the train approaches a full stop.

In automatic air-brake systems,such as the Westinghouse, it is thepractice in making an emergency application of brakes to vent both theauxiliary reservoir and the train-pipe into the brake cylinder in orderthat an extra pressure may be obtained. This venting of the train-pipeinto the cylinders not only hastens the stop by furnishing extrapressure, but incidentally accelerates the response of the triple valvesthroughout the train.

In the practice of my invention I utilize the standard (Westinghouse)capacity relation between the auxiliary reservoir and the brakecylinderand limit the pressure which shallv enter the brake-cylinder in eitherservice or emergency application of brakes to a predetermined amount ineach, and then by increasing the leverage of the brake-rigging I am ableto secure the desired maximum brake stress in emergencies.

My invention not only serves to automatically limit the service-pressurein the brakecylinder to,say, forty pounds per square inch, (the alteredleverage in the brake-rigging giving the desired results with thispressure,) but it also provides means for automatically reducing to apredetermined proportion to the pressure remaining in the auxiliary reservoir any pressure which may enter the brake-cylinder in excess of themaximum desired. Further, the use of diaphragms instead of pistonsprecludes the possibility of leakage, which might render the deviceinoperative. In these respects my present device constitutes a materialimprovement on that pauying drawing, which represents a section of astandard Westinghouse triple valve with my improved valve fittedthereto.

Referring to the drawing by letter, A represents the triple valve ofordinary construetion and operation; B, the port leading to thebrake-cylinder (not shown) through a suitable pipe b; O, the auxiliaryreservoir, and c the port leading from the auxiliary reservoir to thetriple valve. p

D is the casing of my improved valve, preferably secured between thetriple valve and the reservoir or cylinder, to which the triple valve isusually attached. It contains two diaphragms d and d on a common stem (1carrying two valves, one designated herein as the intercepting-valve dcontrolling the passagefrom the auxiliary to the triple, and the otherthe discharge-valve d governing the escape-port a, leading to theatmosphere, for brake-cylinder pressure. Both valves are rubber-seated.The area of the diaphragm cl is about one-third larger than that of d;but this proportion may of course be varied as desired. The stem of theinterceptingvalve projects loosely through a yoke d and carries a head(Z which engages with the yoke. The discharge-valve 61 which is .hollow,carries an end cap d through which the stem passes, the stem terminatingin a head 01 with which the cap may engage. The valve contains a spring01 bearing against the head (1 through which the valve is seated on themovement of the diaphragms to the left. The head 61 and the cap d areboth provided with air-passages, (shown in dotted lines,) and the valveis pierced laterally to connect port a with its interior chamber. Theport a, by which air from the brake-cylinder passage passes to thedischarge-valve idescribed and claimed in Letters Patent granted to meDecember 31, 1895, No. 522,324. 1 My'invention is illustrated in theaccom-' ICO a and larger diaphragm d, is restricted, as shown. In theusual service applications of the brakes auxiliary-reservoir pressure isadmitted by the triple valve comparatively slowly into thebrake-cylinder passage and passes slowly to the larger diaphragm d byreason of the restriction of the port a. Should the amount of pressureexpanded thus into the brake-cylinder by the triple valve exceedtwo-thirds of the remaining auxiliary-reserv0ir pressure upon thesmaller diaphragm d,

it will be seen that the larger diaphragm (1 will over-balance the otherby reason of the relative sizes of the diaphragms and both will beforced to the right, carrying with them both valves, closingcommunication between the auxiliary reservoir and the triple valve andopening the escape-port a for a comparatively slow release ofbrake-cylinder pressure. This depletion of cylinder-pressure willcontinue until the relative pressures in reservoir and cylinder areagain established, when a further depletion will cause theslightly-preponderating pressure on the smaller diaphragm (Z to slowlymove both diaphragms to the left, seating the discharge-valve d Furthermotion to the left will then be arrested by the resistance of the springd and of the intercepting-valve (1 as at this point the yoke (Z willcome into contact with the head of the intercepting-valve stem and saidvalve will be held to its seat by reason of the slight excess ofpressure on its left side, the area of that side being somewhat largerthan that of its right side. These combined resistances to furthermovement to the left at this time will accordingly serve to checkfurther escape of brake-cylinder pressure, while retaining in theauxiliary reservoir all of its remaining pressure. \Vhen, however,thebrake-cylinder pressure is finally released through the usual movementof the triple valve, pressure on the large diaphragm d will also bereleased through the same port a by which it entered and auxiliarypressure will force all parts to their normal positions, as shown in thedrawing-21 6., dischargevalvc closed and port a and intercepting-valveopen. In an emergency application pressure from the auxiliary reservoiris admitted suddenly and in large volume to the brake-cylinder andattains the maximum degree therein before it has time to actuate thelarger diaphragm (1, because of the restriction of the passage athereto, as heretofore described. It is thus evident that fullemergency-pressure will be obtained in the brake-cylinder and will beimmediately thereafter slowly reduced in the manner before describedthrough ports a and a and valve (1 until the stated proportion toremaining auxiliary pressure is reached, when further escape will bechecked and pressure held in both cylinder and reservoir until brakesare released in the usual manner. It is evident also that this operationwill be the same whenevera full or nearly full expansion of theauxiliary into the brakecylinder takes place, whether in emergency orservice applications, and the highest brakingeificiency will thus beobtained. Further, the increased brake-pressure available by this devicewithout injurious eifeets requires a less amount of air in makingordinary stops and allows a greater number of applications of brakeswithout recharge of auxiliaries. It will also be seen that when holdingbrakes on grades with auxiliary and cylinder pressures nearly or fullyequalized, the triple-valve piston being in its full-applicationposition, it, as frequently happens, the brake-cylinder pressure becomesdepleted by leakage this valve will in the performance of its regularfunctions,'as described herein, automatically admit additional pressureinto the brake-cylinder from the auxiliary reservoir, thus obviating adangerous reduction of brakingpressure.

I am aware that an increase in the leverage of the brake-rigging meansan increased length of stroke for the brake-cylinder pisten; but thisincrease will be slight and of no more consequence than ordinary slackadjustment provides for.

My invention contemplates a differential diaphragm actuated by auxiliaryreservoir and brake-cylinder pressures through a normally-restrictedpassage, first, to control the port leading from the auxiliary reservoirthrough the triple valve to the cylinder; scc- 0nd, to automaticallyreduce any excessive pressure which may for any cause enter thebrake-cylinder, and, third, to automatically reduce to a predeterminedpercentage of the remaining auxiliary-reservoir pressure any pressure inexcess of such percentage which may be vented from said reservoir tosaid cylinder in any application of the brakes.

' It is evident that two diaphragms of any desired areas may be employedin my improved apparatus without departing from the spirit of myinvention, and I do not limit myself in this respect nor as to anyspecial standard of either emergency or service brake-pressures. Instandard systems, such as the lVestinghouse, auxiliary-reservoirpressure is at all times practically free to pass to the triple- Valvecasing, which latteron account of its construction and parts presentsmany opportunities for leakage. It will be seen that myimproved valveretains auxiliary pressure therein at times when such leakages becomemostdangerousas, for instance,when brakes are being held withconsiderable force on grades. Further, as by the action of my improvedvalve the pressure in the triple-valve casing above its piston being atsuch times somewhat less than auxiliary-reservoir pressure, it isevident that when the train-pipe pressure is increased in order torelease brakes the triple-valve piston will be more quickly and readilymoved to the release position than if it was then exposed toauxiliary-reservoir pressure above its piston. These also constituteimportant features of my invention.

IIO

. The two diaphragms of different areas on a common stem may be properlydesignated as a diiferential diaphragm or piston.

Having thus described my 7 invention, I claim 1. In an air-brake systemthe combination of a brake-cylinder and auxiliary reservoir, a triplevalve, a port between the reservoir and triple valve and anintercepting-valve controlling said port, an escape-port forbrakecylinder pressure and a discharge-valve controlling the same, saidintercepting-valve and discharge-valve being on the same stem and meanswhereby the pressure in the brake-cylinder will serve to close theintercepting-valve and open the discharge-valve, substantially asdescribed.

2. In an air-brake system the combination of a brake-cylinder andauxiliary reservoir, a triple valve, a port between the reservoir andtriple valve and an intercepting-valve con trolling said port, anescape-port for brakecylinder pressure and a discharge-valve controllingthe same, and means whereby the pressure in the brake-cylinder willserve to close the intercepting-valve and open the discharge-valve, andthe auxiliary-reservoir pressure thereafter close thedischarge-valve,substantially as described.

3. In an air-brake system the combination of a brake-cylinder andauxiliary reservoir, a triple valve, a port between the reservoir andtriple valve and an intercepting-valve controlling said port, anescape-port for brakecylinder pressure and a discharge-valve controllingthe same and means whereby the pressure in the brake-cylinder will serveto close the intercepting-valve and open the discharge-valve,and theauxiliary-reservoir pressure thereafter close the discharge-valve andopen the intercepting-valve, substantially as described.

4.. In an air-brake system, the combination of a brake-cylinder andauxiliary reservoir, a

triple valve, a port between the reservoir and triple valve and anintercepting-valve controlling said port, an escape-port forbrakecylinder pressure and a discharge-valve controlling the same, andtwo diaphragmsor pis tons of different areas acting together to controlthe intercepting and discharge valves, said diaph ragms or pistons beingrespectively subjected to pressures from the auxiliary res ervoir andthe brake-cylinder, substantially as described.

5. In an air-brake system, the combination of an auxiliary reservoir, atriple valve, a brake-cylinder, a port connecting same, an escape-portfor the brake-cylinder pressure,- valves controlling said ports and adifferential diaphragm actuating said valves, said diaphragm beingsubjected on one side to auxiliary-reservoir pressure and on the otherside to brake-cylinder pressure, substantially as described.

6. In an air-brake system, the combination of an auxiliary reservoir andtriple valve, a port connecting the same, a valve controlling said portand a differential diaphragm actuating said valve, said diaphragm beingsubj ected to auxiliary-reservoir pressure on one side and tobrake-cylinder pressure on the other side. 7

7. In an air-brake system, the combination of an auxiliary reservoir, abrake-cylinder, a passage connecting the same, and a valve deviceexposed to auxiliary-reservoir and brakecylinder pressures and adaptedto automatically produce and maintain a predetermined ratio between saidpressures, substantially as described.

In witness whereof I subscribe my signature in presence of twowitnesses.

WVILLIAM H. CLARKE.

Witnesses:

FRANK S. OBER, JAMES OPPENHEIM.

